High energy femtosecond mid-IR fiber CPA system at 2.79 µm using single mode operation of a coiled 46µm core Er:ZBLAN LMA fiber

We demonstrate the first large-core Er: ZBLAN fiber-based chirped-pulse amplification system operating at ∼2.79 µm. Single-mode amplification in a coiled 46 µm-core, ∼0.064 NA Er:ZBLAN fiber delivers up to ∼144 µJ of stretched femtosecond pulses (∼1.5 ns) at a 5.5 kHz repetition rate. After diffraction-grating compression, ∼70 µJ pulses with a duration of ∼525 fs are obtained. This represents what is believed to be a new record pulse energy for femtosecond-duration Er: ZBLAN fiber lasers, exceeding previous results by nearly two orders of magnitude. The performance is enabled by a diffraction-grating based CPA architecture combined with large-mode-area fiber operating robustly in a single transverse mode.